Addition of cyclopentane to slowly reacting mixtures of H2+ O2 between 673 and 783 K: reactions of H and OH with cyclopentane and of cyclopentyl radicals

Abstract

A number of elementary reactions involved in the oxidation of cyclopentane (CP) have been studied by adding CP to H2–O2 mixtures over the temperature range 673–783 K. Kinetic studies of the relative rates of consumption of CP and H2 have given values of k21=(1.11 ± 0.25)× 1010 and k22=(1.84 ± 0.32)× 109 dm3 mol–1 s–1 at 753 K. Combination with independent data and critical analysis gives k21= 3.65 × 102T2.5 exp(519/T) dm3 mol–1 s–1, which is recommended between 250 and 1500 K, with error limits of 50 Torr, very little ring rupture has been observed in the initial products. The formation of C2H4 has been discussed in detail, and a value of k32= 1013.14 ± 0.55 exp(– 17260/T) s–1 has been obtained over the temperature range 580–783 K. c-C5H9→ CH2= CHCH2CH2CH2(32) The cyclisation of C3, C4, C5 and C6 alken-1-yl radicals has been discussed and it has been concluded that the predominant reaction of hex-5-en-1-yl radicals between 600 and 1300 K and at 1 atm O2 pressure is cyclisation giving c-hexyl radicals. As the latter rapidly undergo successive oxidation to cyclohexene, cyclohexadiene and then benzene, it has been further concluded that such C6 cyclisations could be major sources of benzene and substituted benzenes in the oxidation of conventional fuels.